ANOSOGNOSIA DURING INTRACAROTID BARBITURATE ANESTHESIA - UNAWARENESS OR AMNESIA FOR WEAKNESS

Previous studies have demonstrated asymmetric hemispheric contribution s to deficit awareness during hemisphere inactivation with intracaroti d barbiturate infusion (Wada studies). These observations provide insi ght into the neuropsychological basis of anosognosia for hemiparesis ( AHP), arguing against earlier explanations based upon psychological de nial, global cognitive disturbance, or emotional indifference. Althoug h prior Wada studies equated AHP after the procedure with AHP during t he period of deficit, a selective memory failure could also account fo r these findings. We, therefore, assessed the occurrence of AHP during and after right-hemisphere inactivation in a group of epilepsy patien ts undergoing preoperative Wada testing. Because aphasia obscures asse ssment of deficit awareness during left carotid studies, we compared t he frequency of AHP between right- and left-hemisphere inactivation on ly after recovery. As noted in earlier reports, AHP was present signif icantly more often after right- than left-hemisphere inactivation. The proportions of subjects with AHP during right-hemisphere anesthesia c ompared with the proportion of subjects with AHP after the procedure w ere statistically equivalent, suggesting that the AHP observed after r ight-hemisphere anesthesia results from true failure of deficit awaren ess rather than inability to recall the deficit.